While CT is being used in all aspects of medical diagnosis, a dramatic increase in the use of cone beam CT (CBCT), a form of CT, has occurred in dentistry during the last decade. In particular this technology has found application in orthodontic treatment planning, which is often initiated in young patients. The currently available data regarding dose and risk to patients undergoing CBCT are incomplete and underestimate the risk to pediatric patients. Moreover, current techniques for measuring patient dose/risk from CBCT examinations are either excessively complex or unreliable. To address these important issues we propose a thorough investigation of CBCT dosimetery and the development of a simple device that may be used to inexpensively and accurately determine patient dose and measure image quality. This will be accomplished through first conducting a thorough dosimetry investigation of current CBCT machines using an anthropomorphic phantom. Exposure variables such as current (mA), exposure time(s), and peak kilovoltage (kVp) will be evaluated so that the effect of each of these variables on patient risk can be estimated. Modulation transfer function (MTF) and Contrast to noise ratio (CNR) will be calculated as objective measures of image quality. This data will then be used to develop a simple and inexpensive method to accurately determine effective dose and image quality using readings from a simple Plexiglas phantom with a minimal number of dosimeters. This simplified phantom device will promote accurate and standardized reporting of dose for risk estimation of CBCT examinations.